diff --git a/tripleo_common/tests/test_update.py b/tripleo_common/tests/test_update.py
index e004dadca..cde9c81c6 100644
--- a/tripleo_common/tests/test_update.py
+++ b/tripleo_common/tests/test_update.py
@@ -48,7 +48,7 @@ class UpdateManagerTest(base.TestCase):
             'stack_id': 'stack_id',
             'template': 'template body',
             'files': {},
-            'parameters': {'UpdateIdentifier': 123},
+            'parameters': {'UpdateIdentifier': 123, 'StackAction': 'UPDATE'},
             'environment': {
                 'resource_registry': {
                     'resources': {
diff --git a/tripleo_common/update.py b/tripleo_common/update.py
index 87ce9ea3b..9c85b2471 100644
--- a/tripleo_common/update.py
+++ b/tripleo_common/update.py
@@ -49,7 +49,7 @@ class PackageUpdateManager(_stack_update.StackUpdateManager):
         # time rounded to seconds
         timestamp = int(time.time())
 
-        stack_params = {'UpdateIdentifier': timestamp}
+        stack_params = {'UpdateIdentifier': timestamp, 'StackAction': 'UPDATE'}
 
         tpl_files, template = template_utils.get_template_contents(
             template_file=os.path.join(self.tht_dir, constants.TEMPLATE_NAME))